PHASE BEHAVIORAL-STUDIES OF THE QUATERNARY SYSTEM OF WATER TX 100 N-BUTANOL NORMAL-HEPTANE + CHOLESTERYL BENZOATE

Results of phase behavioural studies of the quaternary system water/TX 100/n-butanol/ (n-heptane+cholesteryl benzoate) are presented. The pseudoternary phase diagrams are distinct with respect to TX 100/n-butanol ratio; a 1:1 ratio offers a maximum microemulsion zone: other ratios give reduced zones with marked positional shifts. At a ratio of 1:1 the quaternary system is biphasic at 20 and 30°C; at 40 and 50°C it becomes triphasic. At 30% oil the combined percentage of TX 100 and n-butanol required to yield complete microemulsion is a minimum at 30°C; at 60% oil the required percentage is independent of temperature. The additive urea has shown a significant effect; a 6 mol dm-3 urea solution increases the microemulsion zone by about two-fold with a 50% reduction in the TX 100 and n-butanol concentration. At a TX 100/n-butanol ratio of 1:1, the additives NaCl and polyacrylamide considerably increase the volume of the biphasic solutions above critical concentrations of 1 and 0.1 %, respectively. The other polymeric additives, viz. polyethylene glycol and gelatin, exhibit a reduction in the volume of the biphasic solution: a limiting value is offered by the former at the level of 1%. © 1990.